1. Field of the Invention
The invention is directed to the field of water wells, monitor wells and recovery wells for recovering contaminated ground water. In particular, the present invention relates the stimulation of liquid flow into a well from liquid in the strata about the well. Additionally, the present invention relates to removing mineral scaling in the well and formation and to the control of common bacteria, especially, iron-related bacteria that plug up wells.
2. Description of the Prior Art
The prior art techniques for stimulating the flow of water in a dry well or one providing insufficient water often involved drilling the well deeper, drilling shafts transverse to the main well shaft or dynamiting the well in the hope of creating fissures in the strata to provide passages to water supplies. Dynamiting more often than not will destroy the well. Other prior art techniques employed treating agents pumped into the well such as inorganic acids, for example hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, some organic acids forming water soluble salts, for example oxalic acid and acetic acid. Solvents, especially organic solvents, for instance alcohols, hydrocarbons and chlorinated hydrocarbons are also useful as are oxidizing agents such as potassium permangenate, hydrogen peroxide, oxygen and substance yielding oxygen. These techniques are extremely useful in the rehabilitation of oil or gas wells but are not directly useful where potable water is required, since these materials act as water pollutants which must be removed or treated before the water from the well can be used.
An apparatus and method for water flow stimulation in a well is disclosed in U.S. Pat. No. 4,534,413 and U.S. Pat. No. 4,580,629 (the disclosures of these references are incorporated herein by reference). The apparatus disclosed in these patents includes two plates proportioned to be received in a well casing and which were connected by tie rods. A third plate, known as a pressure plate, is located between the tie rod connected plates and a deformable gasket located between the pressure plate and the lower of the two tie rod connected plates acts as the means for sealing the cap in the well. Sealing in the well is accomplished by moving the pressure plate downward toward the lower of the tie rod connected plates.
The embodiments disclosed in these patents provide a relatively simple, direct manner of stimulating the flow or water from water supplies trapped in the strata about a well shaft into such shaft without adversely affecting the potability of the water released. A strong cap is fitted to the well casing to prevent its unwanted removal therefrom and to provide a seal therebetween so that the pressure on the well can be maintained. The cap is provided with fittings to control the introduction of liquid or gaseous nitrogen and liquid or gaseous carbon dioxide into the well and to control the pressure of the gases produced when the liquids go into their gaseous states. The well pressure control also permits the well gas pressure to be reduced to atmospheric pressure as desired. The liquid or gaseous nitrogen and liquid or gaseous carbon dioxide can be introduced into the well individually or jointly. The liquid nitrogen and liquid carbon dioxide are introduced into the well and upon evaporation lower the temperature of the surrounding strata, by absorbing heat therefrom, to a temperature below the freezing point of water thereby freezing the water present in the strata and causing fractures. The liquids are introduced into the well and the resulting gases are retained under desired pressure levels causing the gases to freeze water or water impregnated soil, sand or rock in the wall and thereby expand the fracture. The subsequent release of the well pressure permits the water trapped behind the fractured material to pass into the well under its own pressure. The procedure can be repeated a plurality of times until the flow of water into the well is sufficient. It is therefore an object of this invention to provide a novel method of stimulating water flow into a dry water well or one with low water flow into it.
In commonly assigned U.S. Ser. No. 07/905,793 filed Jun. 29, 1992, now abandoned, an apparatus is disclosed which provides a relatively simple, direct manner of stimulating the flow of liquid from liquid supplies trapped in the strata about a well shaft into such shaft without adversely affecting the potability of the water released. A well cap is fitted to the well casing and/or well screen or the surrounding soil and/or rock walls of the well to prevent unwanted removal of the apparatus therefrom and to provide a seal therebetween so that the pressure on the well can be maintained.
The cap is provided with fittings to control the introduction of liquid or gaseous nitrogen and liquid or gaseous carbon dioxide into the well and to control the pressure of the gases produced when the liquids go into their gaseous states. The well pressure control also permits the well gas pressure to be reduced to atmospheric pressure as desired. The liquid or gaseous nitrogen and liquid or gaseous carbon dioxide can be introduced into the well individually or jointly.
The well cap of this application has a first and second plate means which are so proportioned as to be receivable in a well casing or in the surrounding well walls. A sealing means which extends between the first and second plate means can be actuated by downward movement of the first plate means toward the second plate means which is mounted at the bottom by means of a hydraulic cylinder.
Mounted between pressure plates is a neoprene gasket which is approximately the same width as the plates. When acted upon by piston or plunger, the neoprene gasket trapped between plunger and lower pressure plate is caused to expand outwardly and the grip of the walls of well. The engagement between the periphery of the neoprene gasket and the walls of well serves to hold the position of cap at the desired depth in the well and to seal the well at such depth.
The above-mentioned U.S. patents and patent application are incorporated by reference in total into the present application.
It is another object of these patents to provide a novel method of stimulating water flow into a water well without affecting the quality of the water.
It is another object of these patents to provide a novel method of stimulating water flow into a water well employing solid carbon dioxide.
A further object of this invention is to provide a novel method which can easily be used to control bacteria in a well.
A still further object of this invention is to provide a novel method which can be employed for removing mineral scaling in a well.
The above objects are accomplished by the novel method of the present invention.